Senate President Steve Sweeney says he wants to put the “millionaire’s tax” back on the table as a potential part of filling New Jersey’s $800 million budget gap.

And well he should. The fact that Gov. Christie treats such a tax hike as virtually unthinkable says volumes about the governor’s warped views on sacrifice and everyday living.

Sweeney told the New Jersey State Democratic Committee at its annual conference last week that if Christie’s serious about everything being in play to close the deficit, than the millionaire’s tax should be part of the discussion. He’s right, and he was also correct in complaining that Christie can’t continue to shield the wealthiest residents in the state while demanding more and more from everyone else.

The millionaire’s tax would amount to a small increase in the tax rate on income over a certain high figure — not necessarily a million dollars despite the label. Under former governors Jim McGreevey and Jon Corzine, for instance, higher rates kicked in as soon as $400,000.

Corzine and the Democrats had a chance to renew the tax before Christie took office but opted not to as a political ploy. The idea was to potentially stick Christie with the increase sure to anger the rich and powerful, but Christie has adamantly refused and Republicans invariably point to the Democratic failure to keep the tax alive as one of their justifications.

But the failure to even consider resurrecting some form of the millionaire’s tax is becoming increasingly difficult to defend, as Christie continues to try to squeeze every last drop of blood from the middle-class stone.

Christie likes to spout his mantra about standing firm against raising taxes, but it’s a bogus claim; a variety of increased fees are little different than tax hikes, and the governor’s policies — such as dramatically reduced property-tax rebates — have the net effect of increasing taxes as well.

Particularly exasperating in this debate is the Republican refusal to openly acknowledge the basic truth that the impact on the wealthy of slim tax hikes on high levels of income is largely meaningless. It doesn’t have nearly the practical effect that similar financial demands have on the vast majority of citizens earning far less money, but Christie continues to behave as if he’d rather keep tightening the vise on moderate-income New Jerseyans than dare ask for anything more from those who can most afford it.

The millionaire’s tax is no panacea, and there’s a bit of grandstanding in play here; Sweeney knows Christie would never sign off on a new millionaire’s tax — the governor has vetoed bills approving a hike three times. But the Senate president is emphasizing a principle, and telling the public that when Christie says everything’s on the table, that should mean everything.

There should be no sacred cows in fixing this budget mess. Futile or not, let’s start talking about the millionaire’s tax again.